The field of the invention pertains to automotive trucks with movable bumpers and, in particular, to truck bumpers that can be moved vertically to accommodate the various heights of automobile bumpers. Such bumpers can, of course, be used to push other vehicles with varying bumper heights. The field of the invention also includes various cushioning devices to prevent damage to the bumpers or the vehicles to which the bumpers are attached.
The most commonly employed means for raising and lowering a bumper or snow plow blade are illustrated in U.S. Pat. Nos. 3,332,562 and 3,252,716 respectively. Such devices employ forwardly extending pivotally mounted arms and a diagonally mounted hydraulic cylinder to raise and lower the bumper or blade. An adjustable length chain connects the upper cylinder actuated arm to the blade or bumper.
Much earlier pivoting bumpers are illustrated in U.S. Pat. Nos. 1,208,204 and 2,431,495. Such bumpers utilized supports and actuation means extending longitudinally beneath or above the front axle of the vehicle and were very cumbersome.
Cushioning means for bumpers are illustrated in U.S. Pat. Nos. 3,079,176 and 3,184,253. In the former, the cushioning means are positioned between the bumper and the front of a crawler tractor. The cushioning means reduce the shock of sudden impact with the pushed vehicle. In the latter the cushioning means, in addition to reducing shock loading, also accommodate misalignment between the vehicles thereby reducing stresses in the bumper frames and the tendency to lift vehicle wheels from the ground.
U.S. Pat. Nos. 3,907,353 and 4,026,590 illustrate movable rear truck bumpers to prevent under-ride of following vehicles in the event of a collision. The former may be adjusted vertically by manually adjusting the supporting struts. The latter is not adjustable but rather pivotally folds to provide clearance as the truck body is tilted.
The bumper devices disclosed extend substantial distances in front of or behind the vehicles. The additional length added to the vehicles reduces the maneuverability of the vehicles substantially in proportion to the additional length. The height adjustable bumpers require that the operator exit the vehicle cab or view with mirrors the bumper to ascertain the height thereof. Both methods are cumbersome and time consuming. With a view toward overcoming such deficiencies in the prior art, applicant has invented the bumper disclosed herein.